The present invention relates to truck-mounted brakes for a railroad vehicle and more particularly to an improved single actuator, truck mounted brake.
The accepted truck mounted brakes throughout the railroad industry approved by AAR is a double actuator system known as NYCOPAC sold by New York Air Brake Corporation and its equivalent WABCOPAC sold by Westinghouse Air Brake Corporation. Two actuators are used, one connected to each brake beam on opposite sides of the center axis. An example of the structure is illustrated in U.S. Pat. No. 3,499,507. The next generation of truck mounted brake includes a single actuator, truck mounted brake assembly known as WABCOPAC II. This structure includes a single actuator with a pair of force transmitting arms and a lever connected to the opposite brake beam. A typical example of this structure is illustrated in U.S. Pat. No. 4,793,446.
As illustrated in U.S. Pat. No. 3,499,507, the slack adjuster is provided on the opposite end of the force transmitting device from the actuator and in the opposing brake beam. The NYCOPAC and WABCOPAC have no slack adjuster. In the single actuator system illustrated in U.S. Pat. No. 4,793,446 the slack adjuster is on the return force transmitting device. As discussed therein, it is important that the force transmitting elements and the slack adjuster do not intersect the openings in the bolster for the various angular positions of the force transmitting elements.
The single actuator, truck mounted brake provides a force generated by the brake cylinder multiplied by a factor of four. This system is very effective as a force generated by the brake cylinder is transferred to the center of the arc of each of the shoes equally. The center of the force in the middle of each of the shoes eliminates wasted torsional components that exist in other systems. In extreme arc conditions, the piston in the force actuator is forced to rotate with respect to the cylinder. This provides unnecessary wear and tear on the packing cup and in severe cold weather conditions could cause leakage. Also, the two brake beams are not maintained parallel during operating conditions, providing further deviations in the arc.
A substantial number of cars are equipped with the dual actuator, truck mounted brake, and thus there is a need to provide a single actuator, truck mounted brake system which can be used on existing equipment which was manufactured using dual actuators.
Thus, it is an object of the present invention to provide an improved single actuator, truck mounted brake system which accommodates for extreme arc conditions and severe cold weather.
Another object of the present invention is to provide a single actuator, truck mounted brake system which may be retro-fitted onto existing dual actuator, truck mounted brakes.
These and other objects are attained by mounting a single actuator to a first brake beam in such a manner that the actuator's force transmitting axis is freely maintained coaxial with the transmitting axis of the first force transmitting element which is connected at its other end to a transfer lever on a second brake beam. A second force transmitting element connects another arm of the transfer lever back to the first beam. The mounting structure allows the actuator to rotate about two orthogonal axis. Preferably the mounting structure is a cage which is pivotally rotated to the first brake beam to rotate about the first axis and the actuator is pivotally mounted to the cage to rotate about a second orthogonal axis. The actuator is mounted exterior the first brake beam and includes a slack adjuster extending through the first beam to connect the actuator to the first force transmitting element.
To convert a dual actuator brake system to a single actuator brake system using the previously described elements, the actuator with the first force transmitting elements extending therefrom is mounted at an actuator aperture of the first brake beam using the mounting holes about the periphery of the actuator aperture. The first force transmitting element extends through an opposed force transmitting aperture in the second brake beam. A transfer lever is pivotally mounted to the second brake beam by a bracket using the mounting holes about the actuator aperture of the second brake. The bracket includes an aperture which aligns with the actuator aperture of the second brake beam. The first transmitting element is connected to an arm of the transfer lever. A second force transmitting element is extended through the actuator aperture of the second brake beam and into the force transmitting aperture of the first brake beam. The second force transmitting element at one end is connected to an opposite arm of the transfer lever and its other end is connected to the first brake beam at the force transmitting aperture of the first brake beam using the existing mounting holes.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.